Electromagnetic signalling system

ABSTRACT

A signalling system comprises a trackway which is divided into a plurality of sequential signalling sections, a transmitter is arranged in each of said sections and transmits signalling information to a vehicle travelling on the trackway, a receiver is positioned on the vehicle and is arranged to receive the transmission from each of the transmitters, means being provided to enable said receiver to pick out only the signalling information from the transmitter relating to the particular signalling section in which the vehicle is travelling.

[ Apr. 30, 1974 ELECTROMAGNETIC SIGNALLIN SYSTEM [75] Inventor: Birkin, Michael 8., Derby, England [73] Assignee: British Railways Board, London,

England [22] Filed: May 2, 1972 [21] Appl. No.: 249,584

Primary ExaminerGerald M. Forlenza Assistant ExaminerGeorge H. Libman Attorney, Agent, or Firm-Elliott I. Pollock 57 ABSTRACT A signalling system comprises a trackway which is divided into a plurality of sequential signalling sections, a transmitter is arranged in each of said sections and 52] US. Cl. 246/30, 325/51 transmits signalling informatidn to a vehicle travelling [58] Field of Search 246/30; 325/52, 51 on the trackway, a receiver is positioned on the vehicle and is arranged to receive the transmission from [56] Ref renc Cit d each of the transmitters, means being provided to en- UNITED STATES PATENTS able said receiver to pick out only the signalling information from-the transmitter relating to the particular 3,539,924 I 1/1970 Daskalakis et al 325/51 Signalling Section in which the vehicle is travelling.

FOREIGN PATENTS OR APPLICATIONS 721,323 4/1942 Germany 246/30 3 Chums 3 Drawmg TRANSMITTERS l5 /5 75 TRANSMITTER /0 5 7 RECEIVER 6 RAcKwAY 1 2 1" 9 TRANSPONDER TRANSPONDER I J; 7 I

73 T/RANSPONDER ELECTROMAGNETIC SIGNALLING SYSTEM The present invention relates to an electromagnetic signalling system.

Present methods of automatic train control involve the use of signalling loops in the forms of conductors laid adjacent the rails of the railway track and which pass infonnation to the train via an inductive pickup mounted on the train. These conductor loops are expensive, interfere with track maintenance and are vulnerable to damage by either accident or vandalism.

According to the present invention there is provided a signalling system comprising a trackway which is divided into a plurality of sequential signalling sections, a transmitter being arranged in each of said sections and adapted to transmit signalling information to a vehicle travelling on the trackway. A receiver is positioned on the vehicle and arranged to receive the transmission from each of said transmitters, means being provided to enable said receiver to pick out only the signalling information from the transmitter relating to the particular signalling section in which the vehicle is travelling.

The invention has particular application to tracked vehicles such as railway trains but can equally be applied to non-tracked vehicles.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which FIG. 1 is a diagrammatic representation of a railway signalling system.

FIG. 2 is a block diagram of a transmitter and a receiver,

FIG. 3 is a diagrammatic representation of a railway signalling system constructed in accordance with an alternative embodiment of the present invention.

- As shown in FIG. 1 a train travels on a trackway 11 which is divided into'sequential signalling sections 12 and 13. At the beginning of each signallingsection is positioned a signal which indicates to the train whether it is permitted to enter that sectionof the track. In the present invention this signal is in the form of a directional S.H.F. or other form of microwave transmitter 15, for example incorporating a Gunn diode, which is modulated by the signalling information and also by information corresponding to the signal identity.

The transmission from the transmitter 15 is picked up by a receiver 16 on the train and the information con tained in the signal transmission is acted upon.

A transponder 17 is positioned adjacent the track 11 at the beginning of each signalling section. This transponder can be either an active or a passive device of known type e.g., as described in British Pat. Nos. 1,187,130 or 1,068,145. and contains coded information relating to the identity of the signal ahead. This information is transmitted to a suitable receiver on the train as it passes.

Conventional colour light signals 18 may also be provided at each signal to provide a visual indication corresponding to the information being transmitted by the transmitter 15.

The information passed to the train borne equipment by each transponder l7, comprisesa coded number, in binary digital form, which uniquely identifies the transponder. Each transponder 17 will transmit a different number from all the other transponders along a given stretch of railway track. The messages, or telegrams,

issued to the receiving equipment carried by the train by each of the transmitters l5 also train borne a coded identified number which corresponds to the number given to the equipment by the preceding transponder 17. The traiborne equipment only acts upon the information contained in the telegram if the coded identity of the telegram corresponds exactly with the coded identity of the transponder which has just been passed.

. The object of using a uniquely, identified transponder 'to enable the train borne equipment to pick out the appropriate transmission, is to prevent the equipment from acting upon information contained in the telegram from a transmitter 15 in the vicinity, which relates either to another track or another signalling section some way in the distance, and which does not relate to the next signalling section to be traversed by the vehicle.

FIG. 2 shows the transmitter 15 and receiver 16 in more detail. In the transmitter 15, a command signal to be transmitted is fed in digital form into a modulator 19 which is connected to a microwave power generator 20. This command signal is preferably in the form of a digitally coded signal derived from a read-only memory store, the appropriate memory being activated in dependence upon the information, such as signal aspect, to be transmitted to the train. An appropriate circuit arrangement is described in the specification of Birkin US, Pat. application No. 188,065 filed Oct. 12, 1971, for Improvements Relating to Track to Train Communication Systems? The F.M. output from the generator 20 is fed to a transmitting antenna 21 from which the signal is transmitted in the form of a continuously repeated telegram.

The receiver 16 comprises an antenna 22 which feeds into a mixer circuit 23. A local oscillator 24 operating at a fixed frequency also feeds into the mixer 23. The signal from the mixer is amplified in an amplifier 25 passed to an F .M. limiter and detector circuit 26. This circuit 26 detects the coded digital information contained in the transmitted signal and actuates an appropriate output or outputs to perform the necessary control functions in dependence upon the information contained in the signal. A suitable detector and control circuit is described in Birkin US. Pat. application No. 214,889 filed Jan. 3, 1972, for Improved Signalling System.

As shown in the drawing, the train may be in a position to receive a transmission from more than one transmitter 15. Normally as the transmission. would be line of sight the nearest transmitter 15 facing the train gives the strongest carrier level and would be captured and used by the train. If however this transmission is further in the distance the identity of the signal would not match that given to the train by the transponder l7 and a safe failure would be declared.

An essential feature of the ability to capture the transmission is the use of constant amplitude modula- .tion such as phase or frequency modulation, (angle modulation.)

receiving equipment (similar to 16 in FIGS. 1 and 2) signal transmitted by the transmitter is divided into two sequentially transmitted sections, each relating to one of the two lines 11a or 11b and each of which includes a coded portion which corresponds to the identity of the transponder 17a or 17b for that particular line. The receiving equipment on the train picks out the information relative to the running line which it was traversing. 4

As an extension of the system just described, it would be possible for the transmitter 15 and the receiver 16 to each be in the form of a combined transmitter and receiver. in this way. information such as vehicle identity, vehicle speed etc can be transmitted by the transmitter on the vehicle and picked up by the receiver on the signal 14 and passed to a suitable information display in a signal box for example.

I claim:

1. A signalling system comprising a trackway which is divided into a plurality of sequential signalling sections, a directional radio transmitter arranged in each of said sections, each said transmitter being operative to effect a transmission containing signalling information including an address to a vehicle travelling on the trackway, a radio receiver positioned on said vehicle and arranged to receive the transmission from each of said radio transmitters, and localized means positioned adjacent the trackway for providing to the vehicle address information uniquely identifying the transmission which relates to the particular signalling section located in advance of that in which the vehicle is travelling, thereby to enable said receiver to pick out only the J signalling information contained in that transmission.

2. A signalling system as claimed in claim 1 wherein 7 sequentially. 

1. A signalling system comprising a trackway which is divided into a plurality of sequential signalling sections, a directional radio transmitter arranged in each of said sections, each said transmitter being operative to effect a transmission containing signalling information including an address to a vehicle travelling on the trackway, a radio receiver positioned on said vehicle and arranged to receive the transmission from each of said radio transmitters, and localized means positioned adjacent the trackway for providing to the vehicle address information uniquely identifying the transmission which relates to the particular signalling section located in advance of that in which the vehicle is travelling, thereby to enable said receiver to pick out only the signalling information contained in that transmission.
 2. A signalling system as claimed in claim 1 wherein said localized means is a transponder.
 3. A signalling system as claimed in claim 2 wherein the trackway is divided in each signalling section into two or more adjacent tracks each providing a path for a vehicle, a single radio transmitter being provided to transmit signalling information for each of said tracks sequentially. 